"He's going for a 10-day trial for the right to play against the likes of Elgin City, Montrose, Clyde and Stirling, and he's going to miss a top of the table clash with Melbourne Victory.

"This is one of Australia's best young talents and he's going to go down to the fourth tier of Scottish football.

"The Scottish Premier League isn't as good as the A-League.

"I don't know what he's thinking, I don't know what the club's thinking."

The Mariners trumpeted Ryan's link with Rangers on Sunday ahead of their 2-0 win over Western Sydney Wanderers which gives them a four-point lead atop the A-League.

"It is a credit to Mat and to our club that Ally (McCoist) was well aware of Mats' ability and potential and immediately offered for him to join Rangers for a training spell," McKinna, the former Mariners coach and present mayor of Gosford, said in a statement.

Ryan is off contract with the Mariners at the end of the A-League season.

Bosnich said Ryan should immediately seek independent advice from the players' union, the PFA, about whether he was making the right move.

The former Aston Villa, Manchester United and Chelsea keeper believes Ryan is capable of playing in a top European league, well above what Rangers could currently offer.